Ion implantation is a process of introducing dopants or impurities into a substrate via bombardment. In semiconductor manufacturing, the dopants are introduced to alter electrical, optical, or mechanical properties. For example, dopants may be introduced into an intrinsic semiconductor substrate to alter the type and level of conductivity of the substrate. In manufacturing an integrated circuit (IC), a precise doping profile provides improved IC performance. To achieve a desired doping profile, one or more dopants may be implanted in the form of ions in various doses and various energy levels.
Ion implantation systems may comprise an ion source and a series of beam-line components. The ion source may comprise a chamber where desired ions are generated. The ion source may also comprise a power supply and an extraction electrode assembly disposed near the chamber. The beam-line components, may include, for example, a mass analyzer, one or more analyzing magnets, a first acceleration or deceleration stage, a collimator, and a second acceleration or deceleration stage. The analyzing magnets select desired ion species, filter out contaminant species and ions having undesirable energies, and adjust ion beam quality at a target wafer. Suitably shaped electrodes may modify the energy and the shape of an ion beam. Much like a series of optical lenses for manipulating a light beam, the beam-line components can filter, focus, and manipulate ions or ion beam having desired species, shape, energy, and other qualities. The ion beam passes through the beam-line components and may be directed toward a substrate mounted on a platen or clamp. The substrate may be moved in one or more dimensions (e.g., translate, rotate, and tilt) in the beam to achieve the desired process results.
Significant changes in ion energies taking place in the optical elements of the beamline components may have a substantial impact on a shape of the ion beam. For example, a deceleration lens used for providing co-local deflection for filtering energetic neutrals, may face challenges associated with control of deflection angle and beam focus. Furthermore, voltage needed to control deflection of the ion beam may depend on the energy of the beam (e.g., input and output), whereas voltage to control focus of the ion beam may be varied to accommodate ion beams with different current and height. This may lead to difficulty in tuning the ion beam since tuning the size of the ion beam (focus) may not be readily feasible if a position of the ion beam also continues to vary. Still furthermore, conventional systems and methods do not provide independently control of the deflection and/or focus of the ion beam.